1. Field of the Invention
The present invention relates to an apparatus for use with a fluids handing device. More specifically, the invention relates to an apparatus for plugging a fluid passage in a tube sheet.
2. Description of the Related Art
Heat exchangers for transferring heat between two different fluids typically employ multiple tubes having an inlet and an outlet both held by a tube sheet. Bores are formed through the tube sheet that register with the end of the tubes. The tubes may experience a leak along their body or where they join with the tube sheet. Corrective action may involve plugging the leaking tube at one or both ends rather than mending the leak itself. A prior art example of a plug assembly 10 is shown in a perspective and partial sectional view in FIG. 1.
In the prior art example of FIG. 1, the plug assembly 10 is set within a tube 12 to provide a pressure and flow barrier through the tube 12. The plug assembly 10 is made up of a tapered plug 14 having a blunt end and a narrow end. The body of the plug 14 narrows linearly from the blunt and narrow ends. An annular compression ring 16 surrounds a portion of the plug 14 and has an undulating outer surface along the length of the ring 16. The undulations fill a radial space between the outer surface of the plug 14 and inner surface of the tube 12. Typically, the plug 14 and an uncompressed compression ring 16 (not shown) are inserted into the tube 12, with the blunt end being inserted first. When initially inserted into the tube 12, the outer diameters of the undulations on the compression ring 16 are exceeded by the inner diameter of the tube 12, so that the plug 14 and uncompressed compression ring 16 may be inserted into the tube 12 largely unimpeded. An installation tool, not shown, having an outer sleeve is inserted into the tube 12. A force F pulls the plug 14 in the direction shown in FIG. 1 while the outer sleeve is held in place against a lateral side of the compression ring 16. The force F urges the plug 14 axially through the ring 16 and the outer sleeve retains the compression ring 16 in place. Continued pulling repositions the plug 14 within the ring 16 so that a larger diameter portion of the plug 14 is circumscribed by the compression ring 16. Continued pulling positions the ring 16 onto larger diameter portions of the plug 14, thereby increasing the force required to slide the ring 16 over the plug 14. Eventually, the resistive sliding force of the increasing diameter of the plug 14 overcomes the yield strength of the compression ring 16 and the ring 16 compresses by the combination of the pulling force F and presence of the sleeve. When axial compressed, portions of the ring 16 radially expand into spaces between the plug 14 and tube 12. The sleeve is then removed from the tube 12 along with the tool that applied the pulling force F. While the undulating peaks on the outer surface of the compression ring 16 can become deformed and provide a tight fit, over time the compression ring 16 may slide along the plug 14 towards the tapered end and introduce a risk of removing the pressure barrier provided by the plug assembly 10.